SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
The EMIF easily interfaces to a variety of asynchronous devices including NOR Flash and SRAM. It can be operated in two major modes (see Table 23-16):
Mode | Function of EM1DQM pins | Operation of EM1CS[4:2] |
---|---|---|
Normal Mode | Byte enables | Active during the entire asynchronous access cycle |
Select Strobe Mode | Byte enables | Active only during the strobe period of an access cycle |
The first mode of operation is normal mode, in which the EM1DQM pins of the EMIF function as byte enables. In this mode, the EM1CS[4:2] pins behave as typical chip select signals, remaining active for the duration of the asynchronous access. See Section 23.2.6.1 for an example interface with multiple 8-bit devices.
The second mode of operation is select strobe mode, in which the EM1CS[4:2] pins act as a strobe, active only during the strobe period of an access. In this mode, the EM1DQM pins of the EMIF function as standard byte enables for reads and writes. A summary of the differences between the two modes of operation are shown in Table 23-16. Refer to Section 23.2.6.4 for the details of asynchronous operations in normal mode, and to Section 23.2.6.5 for the details of asynchronous operations in select strobe mode. The EMIF hardware defaults to normal mode, but can be manually switched to select strobe mode by setting the SS bit in the asynchronous m (m = 1, 2, 3, or 4) configuration register (CEnCFG) (n = 2, 3, or 4). Throughout the chapter, m can hold the values 1, 2, 3 or 4; and n can hold the values 2, 3, or 4.
The EMIF also provides configurable cycle timing parameters and an extended wait mode that allows the connected device to extend the strobe period of an access cycle. The following sections describe the features related to interfacing with external asynchronous devices.